1. Field of the Invention
This invention relates generally to systems for producing adjustable surface contours, such as for control surfaces for aircraft, and more particularly, to a system that produces a variable surface contour of a compliant, continuous surface.
2. Description of the Related Art
A need for surfaces having an adjustable or variable contour is present in a wide variety of applications, ranging from aircraft control surfaces to specialized furniture. Absent the ability to vary the surface contour in any, such application results in the creation of products and systems that are not optimally designed, but instead are configured as compromises between conflicting design goals. In the case of airfoils for aircraft, it is known that overall drag results from the combination of friction between the airfoil and the air flowing therearound, and the lift component of force supplied to an aircraft wing. In such an application, innumerable variations can be effected between airfoil thickness, airfoil camber, airfoil length and width, and the like. The conventional airfoil, therefore, is but the implementation of an engineering compromise to effect an acceptable lift:drag ratio, which is a primary flight control parameter. There is a need, therefore, for an arrangement that enables advantageous variation in the shape of an airfoil and the contour of the associated control surfaces.
There is a need for an arrangement for varying the dimensions and contours of airfoils, such as aircraft wings, so as to optimize same for different flight conditions Thus, for example, the wing configuration that would be optimum for stable, undisturbed flight, would be different from the wing configuration that would be optimized during take-off and landing: It would additionally be advantageous if the contour of the airfoil is adjusted in a manner that is not constant throughout the length of the airfoil, but which varies, illustratively to form a twist along the control surface of the wing. There is a need for optimizing the configuration and contour of such surfaces in other applications, such as in hydrofoils for water craft and spoilers for high speed land vehicles.
In addition to the foregoing, there is a need for a system that affords advantageous variation of a surface contour for applications unrelated to airfoils, hydrofoils, spoilers,.and the like. Such other applications may include, for example, adjustable seating surfaces, including back supports as well as fluid passageways, the dimensions of which are desired to be varied, such as an air intake passageway for an engine of a vehicle.
It is, therefore, an object of this invention to provide a simple and economical arrangement for varying a contour of a surface.
It is also an object of this invention to provide an airfoil having an adjustable configuration.
The foregoing and other objects are achieved by this invention which provides in a first apparatus aspect thereof an arrangement for producing a variable contour of a compliant surface. In accordance with the invention there is provided a compliant frame member having a predetermined contour arranged to communicate with the compliant surface. An actuator element is arranged in predetermined first relation with respect to the compliant frame member, and there is further provided at least one linkage member coupled at a first end thereof to the compliant frame member, and at a second end thereof to the actuator element. With this arrangement, displacement of the actuator element results in a corresponding displacement of the contour of the compliant frame member. The linkage element has a predetermined resilience characteristic.
In one embodiment, the predetermined resilience characteristic of said linkage element has a directional aspect. Such a directional aspect of the predetermined resilience characteristic can correspond to a resilient compression characteristic, and in other embodiments, to a resilient lateral deflection characteristic. A resilient lateral deflection characteristic would correspond to a resilient lateral beam load response.
In an advantageous embodiment of the invention, the compliant frame member, the actuator element, and the linkage element are integrally formed. In a further embodiment, the displacement of the actuator element is transmitted via the linkage element to produce a substantially orthogonal displacement of the compliant frame member. Thus, the displacement of the actuator element and the corresponding displacement of the compliant frame member are not necessarily in the same plane.
In a farther embodiment there is provided a plurality of further linkage elements, each coupled at a respective first end thereof to the compliant frame member at a predetermined location thereof The plurality of further linkage elements are each coupled at a second end thereof to the actuator element. Displacement of the actuator element results in a corresponding displacement of a contour of the compliant frame member. In embodiments where the actuator element has a determined configuration, the plurality of further linkage elements are each coupled at respective second ends thereof at predetermined locations of the actuator element. The actuator element may be displaced angularly to achieve a desired displacement of the compliant frame member and thereby achieve a predetermined corresponding displacement of the contour of the compliant frame member. Such angular displacement may be in the form of rotation in a direction parallel to the plane of the compliant frame member, or about an axis substantially parallel to that plane, whereby the actuator element is rotatable in a direction transverse to the plane of the compliant frame element.
In a further embodiment of the invention, there is provided a second actuator element coupled to the actuator element. An additional linkage element is coupled at a first end thereof to the compliant frame member at a predetermined location thereof, and at a second end thereof to the second actuator elements. In this manner, displacement of the second actuator element, in response to displacement of the actuator element, results in a determinable displacement of the contour of the compliant frame member, and consequently, achieves a desired change in the contour of the compliant surface. In one embodiment of the invention, a plurality of further linkage elements are each coupled at a respective first end thereof to the compliant frame member at a predetermined location thereof, and at a second end thereof to the actuator element. The linkage element and the further linkage elements have a determined compliance characteristic that enables transmission there along of a load to the compliant frame, whereby a rotatory displacement of the actuator element results in a corresponding displacement of the contour of the compliant frame member. In a further embodiment, the actuator element is displaced radially, and such radial displacement causes to be transmitted along the various linkage elements, in a manner that corresponds to their respective compliance characteristics, a load that is delivered to the compliant frame member.
As previously stated, the compliant surface, the contour of which advantageously is varied in accordance with the invention herein, is the surface of an airfoil. In such an embodiment, the airfoil is adjusted in its configuration to achieve optimization for a particular flight condition. However, the present invention provides advantages in airfoils that are not directly related to flight, such as effecting an effective deicing procedure of the surface of an airfoil. The advantageously adjustable surface contour of the present invention can be applied to the surface of a rotor blade of a rotary wing aircraft, or the surface of a hydrofoil. Also, the compliance surface can be arranged in an air inlet of an engine or other fluid passageway to effect desired fluid flow characteristics.
In accordance with a further apparatus aspect of the invention, there is provided an airfoil of a type having a substantially longitudinal axis arranged transverse to a direction of travel of the airfoil through a fluid medium. The airfoil is provided with a deformable control surface that extends along a substantially longitudinal axis of the airfoil. A plurality of compliant deformation arrangements are disposed sequentially along the substantially longitudinal axis of the airfoil, each of the plurality of compliant deformation arrangements having a respectively associated input for receiving an input force, and being arranged to communicate with the deformable control surface for deforming same in response to the input force that is applied to each of the plurality of compliant deformation arrangements. There is additionally provided a plurality of force transmission elements, each associated with a respective one of the inputs of the plurality of compliant deformation arrangements. The force transmission elements apply the input force to the respectively associated one of the plurality of compliant deformation arrangements for displacing same correspondingly. In this manner, the deformable control surface is responsively deformed.
In one embodiment, the force transmission elements have a directional predetermined resilience characteristic. Such a directional predetermined resilience characteristic can correspond to a resilient compression characteristic, and in other embodiments, to a resilient lateral deflection characteristic. A resilient lateral deflection characteristic would correspond to a resilient lateral beam load response, as previously noted.
In one embodiment of this further aspect of the invention, the plurality of force transmission elements are each coupled to a drive system. The drive system may include a drive shaft that extends substantially parallel to the substantially longitudinal axis of the airfoil. The force transmission elements are each engaged with the drive shaft, each such engagement being characterized by a respectively associated mechanical advantage characteristic that determines a corresponding extend of deformation of the deformable control surface. For example, the mechanical advantage characteristic may be determined by a screw thread pitch and the direction of rotation.
Further in accordance with this further aspect of the invention, there is additionally provided a plurality of second compliant deformation arrangements, each having a respectively associated input for receiving a respective input force and arranged to communicate with the deformable control surface for deforming same in response to the respective input force applied to each of the plurality of second compliant deformation arrangements.
In one highly advantageous embodiment of this further aspect of the invention, there is provided a drive controller associated with the drive system for controlling the operation thereof in accordance with a selected drive scheme for producing a predeterminable deformation contour of the deformable control surface along the substantially longitudinal axis of the airfoil. In one embodiment, the predeterminable deformation contour of the deformable control surface is selected in response to an operating condition of the airfoil. Such an operating condition, in the context of a wing of an aircraft, may include a normal flight condition, a landing condition, a takeoff condition, or any other condition wherein a predetermined primary flight control characteristic is desired, such as a tailored lift-draft ratio. In addition, there is additionally provided a memory arrangement for storing data responsive to a plurality of selectable drive schemes for achieving a plurality of predeterminable deformation contours of the deformation control surface corresponding to the respective operating conditions of the airfoil. It may be desirable in some embodiments of the invention to effect an overall predeterminable deformation contour for a wing of an aircraft that corresponds to a twist thereof along the length of the airfoil. In achieving such a twist condition, the various sequential compliant deformation arrangements are driven in characteristically different drive conditions to effect the wing twist.
In accordance with a still further apparatus aspect of the invention, there is provided an arrangement for varying a surface contour in response to displacement of an actuator element. In accordance with this aspect of the invention, there is provided a compliant surface having a predetermined surface contour on a first side thereof A compliant frame member having a first predetermined contour characteristic and arranged to communicate with a second side of the compliant surface is provided, whereby an aspect of the first predetermined contour characteristic is imparted to the compliant surface. A linkage element is arranged to be coupled at a first end thereof to the compliant frame member and at a second end thereof to the actuator element. In this manner, displacement of the actuator element results in a corresponding variation in the contour of the compliant frame member. Additionally, there is provided a drive arrangement for displacing the actuator element with respect to the compliant frame member.
In one embodiment of the invention, the compliant frame member, the actuator element, and the linkage element are integrally formed with one another. Such integral formation may be of a compliant polymeric material.
The linkage element has a predetermined compliance characteristic, and in some embodiments, may be substantially rigid. The dimensions, curvature, and compliance characteristic of the linkage elements determine the extent and manner of transmission of forces from the actuator element are delivered to the compliant frame member.
In this further apparatus aspect of the invention, there is provided a drive coupling arrangement, as previously noted, for coupling the drive arrangement to the actuator element in accordance with a predetermined drive characteristic. In some embodiments, the drive characteristic corresponds to a predetermined thread pitch and direction of drive motion. In other embodiments, the drive characteristic may be in accordance with a predetermined cam characteristic. Thus, the actuator element may be moved linearly transverse to the plane of the compliant frame member or angularly with respect thereto. The motion of the driver arrangement can result in rotatory or radial motion of the actuator element. As previously noted, there is additionally provided in some embodiments of the invention a controller for controlling the drive arrangement to achieve a determined surface contour of the compliant surface.
In a further embodiment of the invention, there are provided a plurality of further compliant frame members, each having a respective first predetermined contour characteristic and arranged to communicate with the second side of the compliant surface, whereby an aspect of the respective first predetermined contour characteristic is imparted to the compliant surface. Additionally, there is provided a plurality of further actuator elements and a plurality of further linkage elements coupled at a respective first end thereof to a respectively associated one of the plurality of further compliant frame members, and at a second end thereof to a respectively associated one of the further actuator elements. Thus, displacement of the respectively associated one of the further actuator elements results in a corresponding variation in the contour of the compliant frame member in the vicinity of the respectively associated one of the plurality of further compliant frame members. In a further embodiment, there is provided a plurality of further drive coupling arrangements for coupling the drive arrangement to the respective associated one of a plurality of further actuator elements in accordance with a further predetermined drive characteristic. The predetermined drive characteristic is responsive to a predetermined extended surface contour on the first side of the compliance surface that extends over a plurality of the further compliant frame members.
In one embodiment of this aspect of the invention, the plurality of further compliant frame members are each integrally formed with a respectively associated one of the plurality of further actuator linkage elements. In a still further embodiment, the plurality of further actuator linkage elements are each integrally formed with a respectively associated one of the further actuator elements.
The present invention affords significant advantages over known arrangements for achieving optimization of airfoil control surfaces for various operating conditions. In addition, since there are no external joints or linkages, the present invention is particularly adapted for aircraft arrangements that are intended not to be visible by radar systems. Discrete control surfaces can be achieved with the present invention. As previously stated, lift:drag ratio can be tailored as desired, to achieve greater primary flight control. In addition, as stated, the present invention is not limited to achieving airfoil conditions in specific flight situations, as the invention can be configured to effect in-flight or preflight deicing.